Popping the two fuses sorted the problem.

They're labelled well enough within the fuse box, but the labelling in the manual isn't very clear. "Front Driver Door Controls" meaning "Electric Windows" isn't immediately obvious, in my opinion!!

Resetting the windows was tried before I popped he fuses, but that didn't work as the process assumes the windows are stuck open - whereas mine were stuck closed.

Popping the fuses worked a treat.

Lesson learned - if you're car is icy, resist the urge to open the windows until the ice has thoroughly melted!!

Could have been embarrassing to find the windows were stuck closed on the entrance to a multi-storey car park!!